z axis with pneumatic cylinder ?

Hello,
i like to upgrade my plasma machine with linuxcnc
but i can't disable Z axis probing
because my torch UP and DOWN with pneumatic cylinder and there are ball bearing
kipe the needed distance to metal sheet
please if anyone can help me
thank you so much

More info? Pictures? Videos?

picture

If you keep the pneumatic Z axis, you will not be able to use THC or probing as that needs a controlled axis.
To make the pneumatic work, you just need to do a simple config in LinuxCNC and wire the "torch on" signal to the pneumatic valve so both are turned on at the same time.

Thats a specialised case for HVAC. The default Linuxcnc plasmac config is not designed for that because its designed to probe for the surface on an M3

But you should be able to just create a normal XY machine and use the spindle pins.

Connect spindle.0.enable to your air ram and also connect it as an input to a timedelay component and then connect the time delay output to spindle.0.at-speed pin. Set the time delay to be long enough for the torch to descend to the surface.

so the way linuxcnc works is that the spindle is turned on with an M3 and when the spindle gets to speed, the at-speed pin is enabled. This is the signal for motion to begin. So my proposed solution utilises this at-speed to signal when the torch is ready to be turned on. Also use the timedelay output to turn on the torch.

If you need a pierce delay, just add a G4 dwell after the M3 but I suspect machines such as this cutting thin sheet metal don't need a pierce delay

thank you so much for your reply
@tommylight
i try this but probing still working
@rodw
yes i can use XY machine but plasmaC have many useful featuring this is why i have to use it
my solution is to write programme can emulate probing will z axis moving
i write python code to make some hal connection and everything is ok now.
thank you so much.